【P98】zhxzhx？zhxzhx！

emmmm

#include <iostream>#include <cstdio>#include <cstring>#include <cmath>#include <algorithm>using namespace std;#define LL long longLL n,ans = 0,now = 0;//=A= c++从入门到入土 //QAQ 默默写份题解//qwq 看不懂的地方我们私聊呀~~~~~~~~~ /*    对于（a * b）| x    即 x % ab == 0      设x / ab == c        即 x == abc     设a <= b <= c        则a <= （三次根下n）^ 2 //打不出来数学符号QAQ    这样答案数为 满足 abc <= n  的方案数 */ LL read(){//不讲手读不讲手读     char ch = getchar(); LL x = 0,f = 1;    while(!('0' <= ch && ch <= '9')){if(ch == '-') f = -1; ch = getchar();}    while('0' <= ch && ch <= '9') {x = (x << 3) + (x << 1) + (ch - '0'); ch = getchar();}    return x * f;}// a * b * c == x  a != b != c ;  a = c  b = c  ; a = b = c// i * i * i <= n    i * i <= n / i//也就是 a * a * a <= n  b * b <= n / a int main(){    freopen("a.in","r",stdin);    freopen("a.out","w",stdout);        n = read();now = 0;    for(LL i = 1; (i * i) <= n; i ++){        now += n / (i * i);//a == b        LL s = n / i;        /*            i * i <= n / i    ->   i * i * i <= n            即当前a == b == c == i 合法           */        if(i * i <= s) ans ++,now --;//a == b == c    }//重复情况    ans += now * 3,now = 0;     for(LL i = 1; (i * i) <= (n / i); i ++){        LL s =  n / i;    //  cout << "i " << i << " s " << s << endl;        for(LL j = i + 1; (j * j) <= s; j ++)            now += n / (i * j) - j;            //a b c互不相等 //i就是a j就是b  必有j < c 所以c的取值不能包含<=j的部分     }//排列 a != b != c  3! = 6      ans += 6 * now; now = 0;     //QAQ     printf("%I64d\n",ans);    fclose(stdin);fclose(stdout);    return 0;}